Vitamin c

Vitamin C introduction, Chemistry of Vitamin C, Biochemical Role of Vitamin C, (Collagen formation, Bone formation, Immunological response, Synthesis of Catacholamines, ), Recommended dietary Allowance of Vitamin C, Dietary Sources of Vitamin C, Deficiency symptoms of Vitamin C, Food preparation to retain Vitamin C.

1. Chemistry and Biochemical Role, RDA and Deficiency symptoms of Vitamin C Jasmine Juliet .R Biotechnology Department Agricultural college and Research & Institute Madurai.

2. Vitamin C - Introduction Vitamin C is a water soluble versatile vitamin . It plays an important role in human health and disease.

3. Vitamin C - Chemistry Ascorbic acid is a hexose (6 carbon ) derivative and closely resembles monosaccharides in structure. The acidic property of vitamin C is due to the enolic hydroxyl groups. It is a storing reducing agent , L-Ascorbic acid undergoes oxidation to form dehydroascorbic acid and this reaction is reversible.

4. Vitamin C - Chemistry On hydration, dehydroascorbic acid is irreversibly converted to 2, 3-diketogulonic acid which is inactive. Oxidation of Ascorbic acid is rapid in the presence of copper. Hence vitamin C becomes inactive if the foods are prepared in copper vessels

5. Ascorbic acid ( Vitamin C)

6. Vitamin C – Biosynthesis and Metabolism Many animals can synthesise ascorbic acid from glucose via uronic acid pathway . However , man, other primates, guinea pigs and bats cannot synthesis ascorbic acid due to the deficiency of a single enzyme namely L- gluconolactone oxidase .

7. Vitamin C – Biochemical Functions Most of the functions of vitamin C are related to its property to undergo reversible oxidation -reduction i.e., interconversion of ascorbic acid and dehydroascorbic acid.

8. Vitamin C – Biochemical Functions I. Collagen formation: Vitamin C plays the role of a coenzyme in hydroxylation of proline and lysine while protocollagen is converted to collagen (i.e., Post translational modification). Hydroxyproline and hydroxylysine are essential for the collagen cross-linking and the strength of the fiber . In this way, vitamin C is necessary for maintenance of normal connective tissue and wound healing process .

9. Vitamin C – Biochemical Functions II. Bone formation: Bone tissues possess an organic matrix, collagen and the inorganic calcium, phosphate, etc. Vitamin C is required for bone formation. III. Iron and Hemoglobin metabolism: Ascorbic acid enhances iron absorption by keeping it in the ferrous form. This is due to the reducing property of vitamin C.

10. Vitamin C – Biochemical Functions IV. Tryptophan metabolism: Vitamin C is essential for the hydroxylation of tryptophan (enzyme hydroxylase ) to hydroxy tryptophan in the synthesis of serotonin.

11. Vitamin C – Biochemical Functions V. Synthesis of corticosteroid hormones: Adrenal gland possess high levels of ascorbic acid, particularly in periods of stress, it is believed that vitamin C is necessary for the hydroxylation reactions in the synthesis of corticosteroid hormones.

12. Vitamin C – Biochemical Functions VI. Sparing action of other vitamins: Ascorbic acid is a strong antioxidant . It spares Vitamin A and Vitamin E, and some B complex vitamins from oxidation. VII. Immunological function: Vitamin C enhances the synthesis of immunoglobulins (antibodies) and increases the phagocytic action of leucocytes.

13. Vitamin C – Biochemical Functions VIII . Preventive action on chronic diseases: Free radicals are constantly produced in the normal metabolism. They cause serious damage to proteins, lipids, DNA and the cell membranes. The free radicals are implicated in the development of cancer, heart diseases and also ageing. Vitamin C is a strong biological antioxidant , besides vitamin E and β-carotene.

14. Vitamin C - RDA About 60-70mg vitamin C in take per day will meet the adult requirement . Additional intakes (20-40% increase ) are recommended for women during pregnancy and lactation.

15. Vitamin C – Dietary Sources Citrus fruits, gooseberry ( amla ), guava, green vegetables (cabbage, spinach), tomatoes, potatoes (particularly skin) are rich in ascorbic acid. High content of vitamin C is found in adrenal gland and gonads. Milk is a poor source of ascorbic acid.

16. Vitamin C – Deficiency symptoms The deficiency of ascorbic acid results in scurvy. This disease is characterized by: spongy and sore gums , loose teeth, anemia , swollen joints, decreased immunocompetence , delayed wound healing, haemorrhage , osteoporosis , etc.